The prior art includes a number of word recognition systems which digitize spoken words and develop scores for each digitized word. FIG. 1 illustrates a table which is helpful in explaining the concept of the prior art. During an initializing phase of the system, a series of words, for example "cat, dog, mouse," etc., is sequentially read into the system, as a preset vocabaulary list, where it becomes sequentially digitized as scores or values. Each of these words occupies a unique numerical position in a vocabulary list which corresponds to address locations in a memory. Thus, for example, the word "cat" is digitized to a value of score 1 which forms a data word located in a numerical address location corresponding to the position of the word "cat" in the preset vocabulary list. In normal operation, the scores are serially stored in memory as the words are spoken.
During a subsequent recognition stage of the system, if the word "cat" is spoken, in order for the system to recognize it, the system must digitize the spoken word and form a quantized score for it. Then, the entire memory must be searched for an identity with a score written into memory during the earlier initializing phase. Next, the correlation between the score and the word may be made since the address location of the word relates to its position in the present vocabulary. as will be appreciated, this is a time-consuming process which causes the voice recognition system utilizing the prior art method to operate slowly.
Several other major problems exist for the prior art systems. An initial problem is the response time which is a function of the size of the vocabulary.
A further disadvantage is due to the fact that different pronunciations of the same word may not be recognized.
A further disadvantage of the prior art is that a fixed filter accuracy is used for varying size vocabularies.
It should also be noted that the prior art disadvantageously requires words in a vocabulary to be at least a fixed hamming distance apart or else they will be erroneously recognized.